From a server or a native client, you can send whatever RTP packets you want, but you cannot send whatever RTP packets you want from a web client, and you can

From a server or a native client, you can send whatever RTP packets you want, but you cannot send whatever RTP packets you want from a web client, and you cannot have access to the RTP packets from a web client and do whatever you want with them, at least not very easily. We are working on an extension to WebRTC called RtpTransport that would allow for just that, but it's in early stages of design and standardization.